1. Field of the Invention
The invention relates to the pairing of materials for highly stressed machine parts with sliding friction between two surfaces, especially for parallel-plate slide valves in a corrosive environment, wherein the one surface is formed by a hard cobalt alloy applied by surface welding.
2. Description of the Prior Art
An object of the invention is to be able to take up extreme stresses by a novel pairing of materials. Among them are contact pressures up to nearly 500 N/mm.sup.2 (newtons per square millimeter) at rubbing velocities of up to about 0.3 m/s (meter per second). At the same time, however, the material should be sufficiently resistant in a corrosive environment, especially in water and saturated steam in the temperature range between room temperature (20.degree. C.) and 300.degree. C.
Tests have shown that the pairing of materials known so far does not meet the above-mentioned requirements, although according to the present state of our knowledge, the best-suited armor alloys have been used for this purpose, especially with the pairing of materials stellite 6 against stellite 12. Stellite is a trademark for nonferrous alloys of cobalt, chromium and tungsten. Friction welding could not be prevented thereby even if distances of only 100 mm had to be traveled at the above-mentioned contact pressures.